In modern computing systems, large quantities of data need to be stored for later retrieval and archival purposes. A variety of storage mediums, each with its own particular advantages and limitations, can be used to store this data. For example, a hard drive or array of hard drives may provide relatively fast access to stored data. However, the storage space provided by hard drives may be relatively expensive, limited in capacity, and be susceptible to erasure or tampering. Another example of a storage medium is magnetic tape storage. Magnetic tapes have traditionally been less expensive than hard drive storage and very efficient in storing large quantities of data. Magnetic tapes can also have the advantage of being less susceptible to accidental erasure or tampering. However, the inherent linear nature of magnetic tapes can significantly delay access to desired data. For example, when data is requested that is stored on a magnetic tape, the magnetic tape must be loaded into a tape drive and the tape moved to the location on the tape where the desired data is stored.
By utilizing several different kinds of storage medium within a computer system, the advantages of each storage type can be realized and the weaknesses minimized. For example, hard drive storage could be utilized to store commonly accessed data and magnetic tape drives could be used to archive rarely accessed or sensitive data. In this manner, the limited space of a hard drive could be efficiently utilized to provide quick access to commonly used data, and the larger capacity of the tape drive could be used to archive less frequently used data and back up hard drive contents. As the hard drive capacity is filled up, less frequently used data could be transferred to tape drive storage. Additionally, the more secure, less accessible nature of tape drives can be utilized to comply with the government mandated storage of financial and corporate records.
However, managing and accessing data that is distributed across several storage types can be challenging. Ideally, the distributed storage database would be relatively transparent to the users, secure, and easy to access. Additionally, the computer system should require little, if any, human intervention in managing and accessing data.